Utilities often have to cope with the problem of satisfying consumer demand for energy. Energy demands fluctuate widely between peak and off-peak periods. For example, energy demands peak during hot summer days when consumers require air conditioning. One of the ways utilities handle such situations is by employing load management systems. Information is communicated between subscribers and a headend to efficiently manage consumer energy demands.
Other energy services have been developed including utility-based applications such as water, gas, and electric meter readings. In these applications, the headend communicates with- a meter at a subscriber's premises. Often subscribers want to know what their energy cost and usage are at a particular time, for example during a billing period. An existing utility application allows the subscriber to request this information from the utility. The utility first obtains the information from the meter at the subscriber's premises, performs a calculation at the headend and transfers the desired information to the subscriber.
More and more applications have developed including those which extend beyond conventional utility applications. For example, home security and monitoring and the ability to program appliances are applications which can be implemented. These applications are distributed by different companies which use different protocols for both implementation of their services and for compatibility with the devices located on the subscriber premises.
Existing systems for communicating utility applications are closed or proprietary systems which require a specific type of native message compatible with devices located on the subscriber premises. For example, the applications are distributed over a wide area network that is specifically designed to handle the protocol for a particular vendor's application and the device located at the subscriber's premises.
Some signals received over the wide area networks referenced above are used to control the operation of various appliances. In most cases, these appliances consume electrical energy or fossil fuels. In the case of appliances run by electrical motors, utility companies vary the pricing of each unit of power throughout the day, week, month, or year to compensate for the load placed on their power distribution network. These pricing levels are known as price tiers. One outcome of power companies varying the price of electrical energy over time is a reduction in consumption during the high cost time intervals and a greater consumption during the lower cost time intervals. While the initiation of operation of an individual user's electrical appliances immediately after a change in a price tier do not appear to affect the individual user, the operation of many consumers in this manner can create a tremendous load on the power distribution network. For example, some electric motors require six times their normal operating currents during start up. When a number of users turn on, for example, their HVAC (heating, ventilation, and air conditioning) systems, the influx of current may be up to six times the normal load on the power grid. This initial influx can compromise the integrity of the power grid and, at when the power grid is fully loaded, result in a reduction or shut off in the power supplied to homes. These reductions and shut-offs of power are commonly known as brown-outs or black-outs. These events happen due to the reactions of reclosures.
Reclosures are circuit breakers located on utility poles. They guard against excessive current draws on power lines by tripping and resetting three times then by tripping without reset. For example, when a power line breaks (e.g., due to a falling tree), there is generally a current discharge from the power line to ground. The reclosure detects this abnormally high current and opens the current path. After a short interval, the reclosure resets and is tripped by the excessively high current flow. Finally, the reclosure reaches its preset number of retries and stays open. By this operation, the current flowing through the power line is stopped, protecting passersby and property from being caught in the path of the discharge of current. As the downed power line is only one element of a power grid interconnecting a variety of current paths, the power, which would have flowed through the downed power line, is rerouted through other utility lines. While the power is rerouted to compensate for the downed line, some homes near the downed power line may temporarily suffer a brownout or blackout until power is restored. This same brownout or blackout effect may also occur during the change in pricing tiers as mentioned above as reclosures may be repeatedly tripped by high current flows evident following price tier changes.
Accordingly, a need exists to minimize the stress of initial operation current fluxes on power grids.